Static dissipative optical construction

ABSTRACT

A method of making an optical construction that is static-dissipative and includes a static-dissipative layer buried within optical material.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. Ser. No. 10/436,377, filed May12, 2003, now U.S. Pat. No. 7,041,365, the disclosure of which is hereinincorporated by reference.

TECHNICAL FIELD

This invention relates to optical films, and more particularly to staticdissipative optical constructions and articles having buriedstatic-dissipative layers.

BACKGROUND

Optical films such as those used in liquid crystal displays, glazings,and other laminates and layered products demand high lighttransmissivity and ultra-clean appearance. Defects such as particles,non-planar topography, and disproportionate degree of contact (sometimesreferred to as “wet-out”) that are present in an optical film(s),however, can result in undesirable malappearances, and can bedetrimental to the light transmission, the brightness enhancementfunction or clarity of the product. These defects can be, in part, aresult of static charges that are introduced by manufacturing,converting or assembly processes.

For example, static charges can result from a tape (e.g. masking) orother film that is quickly pulled or peeled away from the targetsubstrate/film during processing. These static charges can subsequentlyattract particles that may be near the surface of a film. Particles thateventually land or become anchored on the film can lead to unwantedlight blockages, refracting, or absorbance, depending on the film'soriginal purpose. A non-planar topography can be the result ofnon-uniform shrinkage, warping, or expansion of a film, particularlywhen an area of the film is pinched or mechanically held in place whilemovement or creep occurs with another portion of the film. Anothercause, however, may be static charges that can create the pinched orstationary area, causing binding between film layers and consequentlylead to non-uniform or non-synchronized film changes. The optical defectknown as the “wet-out” phenomenon can occur when differences in opticaltransmission exist between two regions, or when interference patternssuch as “Newton's rings” are observed. (The defect is minimallydetectable when the wet-out is uniform throughout a film product.)Static charges can contribute to non-uniform attraction of particularareas between two layered films, causing wet-out.

Conductive compositions have been developed since the introduction ofconductive polymers such as polyethylenedioxythiophene (PEDT). Someconductive polymers are dispersible in water and alcohol, rendering thema popular choice for conductive coating compositions. Applying thesecompositions onto films (e.g. on the surface) are known to impartanti-static properties even in the absence of significant ambienthumidity. “Anti-static” or static dissipative materials with thesesurface coated conductive compositions are typically characterized ashaving a surface resistivity of less than about 1×10¹² ohms/square and astatic decay time of less than about 2 seconds.

Some conductive compositions, however, may have limited lighttransmissivity, likely due to their highly colored nature, and thereforehave limited use in certain optical film products that require hightransmissivity and clarity, such as optical-grade display films.Moreover, some polymeric coatings can be susceptible to mechanicalabrasion and other undesirable or optically disruptive effects when leftunprotected. Such mechanical disruptions can be quite detrimental foroptical articles. For example, a smudge or scratch on a polymericcoating can result in an undesirable effect when the article is acomputer display.

Static dissipative materials have been developed for industries such ascarpets, electronics, (e.g., IC wafers, sensors, semiconductors) andpackaging. Currently, materials developed for these applications rely onconductive compositions coated onto a surface of a material and leftexposed to the environment, or materials that have anti-static agentswithin its composition, such as by extrusion of a bulk compositionpre-blended with an anti-static agent, or by penetration, absorption, ormigration of an antistatic agent into the composition. There areantistatic agents that require some amount of water (humidity) to beeffectively static dissipative. These are typically the ionic type ofantistatic agents which rely on ionic mobility for the dissipativemechanism. Their effectiveness, however can be reduced as a function ofhumidity—i.e. as relative humidity decreases, the static dissipativeability decreases. Typically, at relative humidities less about 20% RH,ionic anti-static agents may not be effective.

It is therefore desirable to provide an optical article that can bestatic dissipative even when a conductive or anti-static coating hasbeen buried (e.g. protected) by non-conductive material(s), and also bestatic dissipative in lower humidity environments. Optical articles thatcan be both static dissipative and still capable of maintaining desiredlevels of light controlling ability are also needed. Processes formanufacturing optical-grade constructions and articles with minimaldefects caused by static charges would be beneficial.

SUMMARY

The invention provides constructions and articles that arestatic-dissipative. Embodiments of the invention are opticalconstructions that include an optical layer having a static-dissipativelayer and an overlay of another optical layer.

In an aspect, an optical construction can be substantially staticdissipative even when a static-dissipative component or layer ispositioned between at least two optical materials. The constructions canexhibit a surface resistivity greater than about 1×10¹² ohms/square yetremain static-dissipative. An optical construction can have a staticdecay time of less than about two seconds. Exemplary constructions aresufficiently static-dissipative so that the effects of static chargescan be negated, where the charges are present on or near the surface ofthe article.

In a further aspect, optical constructions provided herein are effectivein dissipating static charges in environments having lower relativehumidity.

In accordance with another aspect of the invention, a process isprovided for making a static-dissipative optical construction.Techniques such as co-extrusion and lamination can be implemented.

The details of one or more embodiments of the invention are set forth inthe accompanying drawings and the description below. Other features,objects, and advantages of the invention will be apparent from thedescription and drawings, and from the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional schematic of an embodiment according to theinvention.

FIG. 2 is a cross-sectional schematic of a further embodiment of theinvention, where an optical layer comprises multiple layers.

FIG. 3 is a cross-sectional schematic of yet another embodiment of anoptical construction having multiple optical layers.

FIG. 4 is a cross-sectional schematic of another embodiment of anoptical construction, having more than one buried static-dissipativelayer.

FIG. 5 is a cross-sectional schematic of yet a further embodiment of anoptical construction according to the invention.

Like reference symbols in the various drawings indicate like elements.

DETAILED DESCRIPTION OF EMBODIMENTS

Constructions according to embodiments of the invention can exhibithigher resistivity values, yet sustain effective levels ofstatic-dissipative capability. For clarity, it is noted that althoughthe term “conductive” is often used in the industry to refer to “staticdissipative,” use of these terms herein are not intended to besynonymous. Specifically, a conductive material is considered to have asurface resistivity up to 1×10⁵ ohms/sq, whereas a static-dissipativematerial typically would have a surface resistivity up to 1×10¹²ohms/sq. These terms are generally used to describe materials having aconductive or static-dissipative component or agent on an exposedsurface of the material. It has been surprisingly found, however, thatconstructions having a static-dissipative layer “buried” between layersof substantially non-static-dissipative components can bestatic-dissipative, even though the constructions exhibit higher levelsof surface resistivity. Furthermore, the static decay times can bemaintained even with these higher surface resistivity values.

In accordance with exemplary embodiments of the invention, opticalconstructions and articles are provided that are substantially staticdissipative. The constructions can maintain and be effectivelystatic-dissipative irrespective of the relative humidity in which theyare used or prepared. For example, low humidity levels (e.g. below 15%RH) will not affect the static-dissipative properties of the opticalconstructions. Thus, advantageously, an amount of moisture need notexist for the constructions to acquire or maintain theirstatic-dissipative property. The optical constructions are alsostatic-dissipative even in the absence of circuitry (e.g., wires)connected to the static-dissipative layer. Exemplary constructions ofthe invention exhibit sufficient static dissipation ability to preventdust, dirt, and other particles from adhering to the surface(s) of theoptical construction. Surprisingly, certain constructions according tothe invention can exhibit a surface resistivity greater than about1×10¹² ohms/sq., and exemplary constructions can have even greatersurface resistivity, such as greater than about 1×10¹³ ohms/sq., yetmaintain their static dissipation ability. Embodiments of the inventionexhibit static decay times of less than about 2 seconds. Other inventiveconstructions can exhibit static decay times of less than about 0.5seconds, while further embodiments can have static decay times of lessthan about 0.1 seconds.

Static-dissipative optical constructions according to the inventioninclude a static-dissipative component adjacently positioned betweennon-static-dissipative optical components such as what is illustrated inFIG. 1. The relative positions of the static-dissipative component inrelation to the non-static-dissipative optical components can be suchthat the static-dissipative component is, for example, buried,sandwiched, covered, overcoated or overlayed by thenon-static-dissipative optical components. Referring now to FIG. 1, amulti-layer optical construction 100 is illustrated, having astatic-dissipative component 10 positioned betweennon-static-dissipative materials 50, 55. Non-static-dissipativematerials 50, 55 need not be the same material. Optionally, the opticalconstructions can include additional layers beyond that over a mereovercoat or protective layer for the static-dissipative coating. Such anembodiment is illustrated in FIGS. 2 and 3, where the static-dissipativelayer in each construction is buried on at least one side, by more thanone non-static-dissipative optical layer. FIG. 2 provides across-section of an optical construction 200 having optical layers 60,65 positioned on interface surface 29 of static-dissipative layer 20. InFIG. 3, a cross-section of an optical construction 300 has astatic-dissipative layer 30 surrounded on each side by two layers, whereone major surface 32 of static dissipative layer 30 is positioned overnon-static-dissipative optical layers 70, 75 and the other major surface34 is overlayed by coextending optical layers 77, 79. In a furtherembodiment, FIG. 4 illustrates the cross-section of an opticalconstruction 400 having more than one static-dissipative layer buriedwithin layers of optical layers. Static-dissipative layers 40, 50 areinterlaced between optical layers 80, 85, and 89 as shown. Optical layer87 is optional, but shown here for illustrative purposes. Theseconstructions having a plurality of optical layers that surround thestatic-dissipative layer may still be able to achieve and retain thestatic-dissipative properties.

Advantageously, constructions according to the invention can be used foroptical articles or devices, where light is intentionally enhanced,manipulated, controlled, maintained, transmitted, reflected, refracted,absorbed, etc. Useful articles, include, but are not limited to, imagelenses, ophthalmic lenses, mirrors, displays (e.g. for computers,televisions, etc.), films, glazings (e.g., windshields, windows), videodiscs, and the like. Constructions according to embodiments of theinvention are useful in devices or articles that do not require thestatic-dissipative layer to be connected to electronic circuitry (e.g.,grounding wires, capacitors, resistors, etc.). Various optical articles,however, particularly those useful in the display industry (e.g. LCD andother electronic displays) can be achieved. These can requireconstructions having high light transmissivity, such as above about 90%,sometimes above about 92%. Other optical display units that can be madefrom structures of the invention include, for example, a backlit LCDdisplay.

The optical layers included in exemplary optical constructions accordingto the invention can serve as a substrate upon which thestatic-dissipative component is applied, and/or as an overlay positionedto cover, surround, or sandwich the static-dissipative component orlayer. As an overlay, an optical layer can be used to protect thestatic-dissipative component from mechanical abrasions, oxidativedegradation, chemical contamination, and other harmful effects. This isparticularly advantageous when an optical construction is used indevices or articles that need protection from manufacturing or handlingenvironments. As a substrate, an optical layer can be used to hold orcarry a static-dissipative layer that, for example, is applied bycoating techniques. In certain constructions of the invention, at leastone of the optical layers has some contact with the static-dissipativelayer as is illustrated in FIG. 5. An optical layer can also be insubstantial contact with the static-dissipative layer. Referring now toFIG. 5, an optical construction 500 is illustrated, havingstatic-dissipative layer 60 positioned between optical layers 90, 95. Asshown in the figure optical layer 90 can be in substantial contact withlayer 60, while optical layer 95 can be considered to have some or aportion of its surface 97 contacting layer 60. Surface 95 can, forexample, have a non-planar topography, yet is capable of achieving aninterface with layer 60. The non-planar topography can be regular (e.g.,substantially uniform) or irregular (e.g., substantially random).

Any material acceptable and useful in optical constructions and articlescan be used for the optical layers. Optical layers are preferablynon-static-dissipative. Useful optical layers are generally purelypolymeric and can therefore be substantially free of static-dissipativeagents, such as agents or additives intentionally included or blendedinto the polymeric material when the layer was formed. Opticalconstructions according to embodiments of the invention can also utilizeoptical non-static-dissipative layers that are substantially free of anystatic-dissipative agents that have leached or penetrated into thepolymeric material.

The non-static-dissipative optical layers in constructions of theinvention can be in the form of a coating or a film. When formed by acoating, a non-static-dissipative optical layer can comprise a resin,such as a hardenable or curable resin. Useful resins include acrylic orepoxy-based, but other resins suitable for optical devices or articlescan be used. The non-static-dissipative coating is typically cured ordried upon its application over the static-dissipative component. UVcuring, for example, can be used to cure the coating composition.

For non-static-dissipative optical layers that are provided in the formof a film, the layer can be made from a variety of materials comprising,for example, polymeric compounds. The film also can be a material made,for example, from a hydrophobic organic polymer with a glass transitiontemperature value (Tg) of at least 40° C. Other polymers having a Tgvalue above 100° C. can be useful. The non-static-dissipative opticallayer can be a material that falls into any of a variety of opticallyuseful classes of material that have optical functions, such aspolarizers, interference polarizers, reflective polarizers, diffusers,colored optical films, mirrors, louvered optical film, light controlfilms, transparent sheets, brightness enhancement film, and the like.The layers can be optically effective over diverse portions of theultraviolet, visible, and infrared spectra. An example of a suitableoptical layer a brightness enhancement film, available under thetradename VIKUITI™ (available from 3M Co.; St. Paul, Minn.). Otherhighly light transmissive films can be used. The thickness of anon-static-dissipative optical layer can be greater than about 2 μm, andalso greater than 5 μm. The layer can also be less than about 10 mm.Typical optical layers will have a thickness of about 75 to about 175μm. Optional features of non-static-dissipative optical layers inexemplary constructions of the invention include a micro-structuredsurface, or a multi-layer construction (e.g. multi-layer optical filmsknown as MOFs).

Examples of suitable materials for the non-static-dissipative opticallayers in exemplary constructions of the invention can be substrates orfilms, that include, but are not limited to, a polyester, polyolefin,styrene, polypropylene, cellophane, diacetylcellulose, TAC or cellulosetriacetate, acetylcellulose butyrate, polyvinylidene chloride, polyvinylalcohol, ethylene-vinyl alcohol, syndiotactic polystyrene,polycarbonate, polymethylmethacrylate, polymethylpentene, norborneneresin, polyetherketone, polyethersulfone, polysulfone,polyetherketoneimide, polyimide, fluorine-containing resin, nylon,acryl, polyacrylate, vitreous materials, glass, or combinations thereof.Other materials that are highly transparent and/or highly lighttransmissive can be used. Films that are easily adaptable to processing,such as polymeric films made of triacetylcellulose (cellulosetriacetate) or polycarbonate, may be quite useful.

Optical constructions of the invention include a static-dissipativecomponent that, although is buried or covered, imparts a staticdissipative property to the optical construction. The static-dissipativecomponent can be provided in the form of a coating, or a layer, ineffective amounts to impart the desirable static dissipative property toa construction, particularly at the article's outermost surface(s). Whenformed by a coating, the static dissipative layer can have a drythickness of at least 2 nanometers.

A static dissipative component can be achieved from a composition havinga conductive polymer dispersed in an aqueous or organic solvent.Suitable conductive polymers include, but are not limited to,polyaniline and derivatives thereof, polypyrrole, and polythiophene andits derivatives. Useful polymers can include, for example, commerciallyavailable conductive polymers such as Baytron™ P (from H.C. Starck;Newton, Mass.). Typically, a conductive polymer can be provided as adispersion. When applied to a non-static-dissipative optical layer, theconductive polymers generally are not expected to migrate or penetrateinto the optical layer.

A static-dissipative composition can also have adhesive properties.Conducting materials suitable for optical use can be included in theseconductive adhesives. For example, these conductive materials includeany one of indium-tin oxide (ITO) aluminum-tin oxide, silver, gold, andthe like, or combinations thereof. These conductive adhesives have usein, for example, LCD displays where a backlight unit includes awedge-shaped edge-lit light guide that has a reflector on its bottom(non-light output) surface. This reflector can be attached to the lightguide using an optically clear conducting adhesive thereby providing astatic dissipative backlight unit.

A binder can optionally be included in the static-dissipativecomposition. Suitable binders are materials that are compatible with theconductive agent or static-dissipating agent (e.g. conductive polymer).Various criteria can be used to characterize suitability of a binder.These include, the binder's ability to form a stable, smooth solution sothat lumps and large particles are minimized or eliminated; the binderwould not cause precipitates to form; the binder would not reduce theeffectiveness of the conductive polymer or agent; and the binder canimpart smooth coatability with minimal streaking or reticulation of thecoating upon drying. Acrylates, urethanes, epoxides, and combinationsthereof are examples of useful optional binders. An acrylic binder canbe similar to what has been described in WO 00/73393. Another usefulbinder is a mixed-acrylate melamine-crosslinked film-forming bindercomposition, as described in WO01/38448A1. Embodiments of the inventionhaving a conductive coating can even utilize a solution supplied underthe tradename CPUD-2™ (available from H.C. Starck) which is acomposition that includes the conductive polymer Baytron P™ premixedwith a urethane binder.

Other additives that are consistent and compatible with thestatic-dissipative agent of the static-dissipative layer and compatiblewith the optical properties of the optical construction can be includedin the static-dissipative composition. These include, but are notlimited to, coating agents, fillers, dopants, anti-oxidants,stabilizers, and the like.

Exemplary embodiments of the invention can be made using any techniquethat can position a static-dissipative component betweennon-static-dissipative optical layers. Some useful processes, include,for example, extrusion, coextrusion, coating, and lamination. In onemethod according to the invention, a static-dissipative opticalconstruction can be made by contacting (such as by coextrusion orlamination), a static-dissipative layer with optical layers to surroundor sandwich the static-dissipative layer. A coextrusion process can, forexample, form a static-dissipative layer at the same time as the opticallayers. Certain conductive polymers may need to be present in acomposition in large concentrations in order for the layers to beformable by bulk-melt techniques. Thus, extrusion or a melt-distributionof a composition having a conductive polymer may require additionalsteps or modifications so that the conductive polymeric compositions canform optically acceptable layers, rather than undesirable, deeplycolored layers. With certain modifications, the compositions can beformulated to be melt-compatible and therefore provide effectively thin,static-dissipative layers.

In another embodiment, a method of making a static-dissipative opticalconstruction can be accomplished by applying an effective amount of astatic-dissipative composition on a surface of a non-static-dissipativeoptical layer and then positioning another non-static-dissipative layerover the static-dissipative composition. Applying the static-dissipativecomposition can be performed using a coating technique. Optionally, aprimer can be applied onto all or some part of a non-static-dissipativeoptical layer, and can be applied prior to applying thestatic-dissipative composition. Another optional step in the process isforming a micro-structured surface on any of the optical layers.

A number of embodiments of the invention have been described.Nevertheless, it will be understood that various modifications may bemade without departing from the spirit and scope of the invention. Theinvention will now be described by way of the following non-limitingexamples. These are provided to illustrate different embodiments anddetails of such. The components and amounts used, as well as otherconditions and details are not intended to limit the scope of theinvention

EXAMPLES

As used herein, the terms “solution,” “dispersion,” and “mixture” aregenerally synonymous. These terms to refer to a generally uniformadmixture of components on a macro scale (e.g. visually) and are notintended to connote a particular state of solubility, particle size ordistribution of the components. Unless otherwise specified, allpercentages are in weight percent.

Test Methods

Surface Resistivity

Surface resistivity of samples was determined using a Model 872 WideRange Resistance Meter and a Model 803B Concentric RingResistance/Resistivity Probe both sold by ETS, Glenside, Pa., accordingto the manufacturer's directions.

Static Decay

Time for decay of surface static charge was determined using an ETSModel 406C Static Decay Meter according to the manufacturer'sdirections. Results stated herein reflect the time required to dissipatean initial surface charge of 5000 volts to 500 volts (i.e., decreasedown to 10% of the original value), and are reported as “Static DecayTime.”

Particle Pick-Up Test

In order to determine whether samples having similar surface resistivityor static decay times react differently in the presence of particulatematter, a use-oriented Particle Pick-up Test was devised.

Fine grade vermiculite having an average particle dimension of about 1mm, was placed at the bottom of a cylindrical plastic container of about3 inch (750 mm) diameter to form a generally uniform layer of about 0.25inch (6 mm) high.

Samples to be tested were rubbed with a material known to induce staticcharges on a surface such as, for example, clean dry human hair, cat furor wool fabric. A coated film sample was gently, randomly rubbed forabout 3-5 seconds against a charge inducing material to induce a staticcharge on the film. The charged film was then positioned on top of thevermiculite container.

The gap between the surface of the vermiculite particles and the surfaceof the charged film was chosen to be either 0.75 inch (19 mm) or 0.5inch (12.5 mm). A 0.75 inch (19 mm) gap was achieved by selecting acontainer with a 1 inch (25 mm) wall height. A 0.5 inch (12.5 mm) gapwas achieved by selecting a container with a 0.75 inch (19 mm) wallheight.

For convenience, the following terms and abbreviations are used in theexamples.

MAB An acrylate core-shell film-forming binder composition describedbelow. IBOA Isobornyl acrylate monomer, e.g., Aldrich Cat. No. 39,210-3MMA Methyl methacrylate monomer, e.g., Aldrich Cat. No. M5,590-9 EAEthyl acrylate monomer, e.g., Aldrich Cat. No. E970-6 HEMA Hydroxyethylmethacrylate monomer, e.g., Aldrich Cat. No. 47,702-8 GMA Glycidylmethacrylate NMP N-Methyl-2-pyrrolidinone, a common solvent BP Aqueousconductive polymer dispersion. Poly(3,4- ethylenedioxythiophene)poly(styrenesulfonate) aqueous dispersion sold by H. C. Starck, Newton,MA, under the tradename “Baytron P”. BP as purchased is understood tocontain 1.3% by weight of conductive polymer. CPUD-2 Baytron ConductivePolyurethane Dispersion II (Baytron CPUD2); An aqueous dispersion ofpoly(3,4- ethylenedioxthiophene)/poly(styrenesulfonic acid)/poly-urethane/triethylamine/1-methyl-2-pyrrolidinone (H. C. Starck; Newton,MA) D1012W ORMECON D1012 W water-based polyaniline dispersion (OrmeconChemie GmbH; Ammersbek, Germany) PET Polyethylene terephthalate filmDBEF VIKUITI ™ Brightness Enhancement Film - a polyester reflectivepolarizer film (3M Co.; St Paul, MN). DBEF-M VIKUITI ™ BrightnessEnhancement Film having a matte surface on one side of the film. (3M;St. Paul, MN). Triton Nonionic surfactant (Aldrich Chemical Co.) X-100Preparation of MAB

A core-shell latex composition comprising a core/shell ratio of 40/60was prepared according to the method described in U.S. Pat. No.5,500,457, Example 1A. The core monomer premix weight ratio wasIBOA/MMA/EA/HEMA=10/10/75/5. The shell monomer premix weight ratio wasIBOA/MMA/EA/HEMA=35/40/20/5. All other ingredients and conditions usedin the preparation were as described. The resultant core-shell latexyielded 34 wt % non-volatile content.

A GMA copolymer composition was prepared as described in U.S. Pat. No.4,098,952, Example 3. The resultant copolymer composition yielded 29 wt% non-volatile content.

MAB was prepared by mixing 67.6 g core-shell latex composition, 144 gGMA copolymer composition, 15 g of a 10% solution of Triton X-100, and773.4 g deionized water to yield a composition containing 6.6% by weightnon-volatile content.

Example 1

A static dissipative film was prepared by coating a conductive polymerlayer onto a non-conductive substrate, and overcoating the conductivepolymer layer with a non-conductive overcoat. A conductive polymermixture was prepared by adding 16 grams of Baytron P dispersion (“BP”)to 84 grams of water with stirring and then adding 0.5 grams of NMP. Theconductive polymer mixture was coated by wire-wound rod onto 0.005 inch(0.125 mm) corona-primed transparent PET substrate to a wet thickness of0.00027 inch (0.0068 mm). The coated substrate was subsequently dried ina forced air oven at 100 C. for 1 minute. A UV-curable acrylic resin,described in U.S. Pat. No. 5,908,847 (Example 1), was warmed to 55 C.and poured onto the BP coated surface of the film. A tool bearing amicrostructured surface was placed onto the liquid acrylic resin coat.The “sandwich” thus formed was pulled through a knife coater adjusted toprovide a final microstructured acrylic layer thickness of about 5-25microns. This sandwich was then cured through the PET substrate side ona Lesco C2020 UV processor (Torrance, Calif.) using two 300 watt Fusion“D” bulbs at 100 percent power at a distance of about 6 inches (150 mm)from the sandwich. The sandwich was put through the processor twice at aline speed of 15 feet/min to ensure thorough cure of the acrylic resin.The microstructured tool was peeled from the sandwich to provide astatic dissipative film having a microstructured surface. Both theacrylic surface and the PET surface of this film had a surfaceresistivity of at least 1×10¹³ ohms/square but had a static decay timeof 0.01 second.

Example 2

A static dissipative film was prepared in accord with Example 1 exceptusing a conductive polymer mixture prepared as follows: 2.5 grams of BPdispersion were added to 90.3 grams of deionized water with mixing. Tothis mixture, with continued stirring were added 6.2 grams of MAB, 0.5grams of NMP and 0.5 grams of a 10% aqueous solution of Triton X-100.Both the acrylic surface and the PET surface of this film had a surfaceresistivity of at least 1×10¹³ ohms/square but had a static decay timeof 0.01 second.

Example 3

A static dissipative film was prepared in the manner of Example 2 exceptno NMP was added to the MAB mixture. Both the acrylic surface and thePET surface of this film had a surface resistivity of at least 1×10¹³ohms/square but had a static decay time of 0.01 second.

Example 4

A static dissipative film was prepared in the manner of Example 3 exceptthat 2.5 grams CPUD-2 dispersion was added in place of the Baytron Pdispersion. Both the acrylic surface and the PET surface of this filmhad a surface resistivity of at least 1×10¹³ ohms/square but had astatic decay time of 0.01 second.

Example 5

A conductive polymer mixture was prepared by mixing together 265 gramsMAB solution, 212.5 grams Baytron P, 85 grams NMP, 85 grams 10% TritonX-100 in water, and 16352 grams of water. Using a wire wound rod, thismixture was coated onto a 0.005 inch (0.125 mm) DBEF-M reflectivepolarizer film which had been previously corona treated in air to yielda 0.001 inch (0.025 mm) wet thickness. The sample was then dried in aforced air oven at 170 F. (75 C.) for approximately 1 minute. For thiscoated film intermediate, surface resistivity of the MAB/BP coated sidewas 1×10⁷ ohms/square whereas surface resistivity of the uncoatedpolyester side was greater than 1×10¹³ ohms/square. Electrostatic decaytimes for either side of this film were 0.01 seconds. To prepare astatic dissipative film as an embodiment of the invention, each side ofthe coated film intermediate was laminated to a 0.005 inch (0.125 mm)transparent polycarbonate film (available from Bayer US; Pittsburgh,Pa.) using a 0.001 inch (0.025 mm) layer of optical adhesive. Surfaceresistivity of each PC side was at least 1×10¹³ ohms/square but bothsides of the film had a static decay time of 0.01 second. During theParticle Pick-up Test, this construction did not attract particulatematter when placed over the bed of vermiculite.

Example 6

A coated film intermediate as in Example 5 was prepared. Onto the MAB/BPsurface was laminated 0.00125 inch (0.03 mm) Soken 1885 transferadhesive (Soken Chemical and Engineering Co, Tokyo, Japan). A sheet of ⅛inch (3.2 mm) poly(methylmethacrylate) (commonly available under thetradename “Plexiglass”) was then laminated to the adhesive surface.Results were observed to be substantially similar to that of Example 5.

Example 7

A static dissipative film was prepared in the manner of Example 5 exceptthe PC film laminated to the MAB/BP side of the coated film intermediatewas 0.010 inch (0.25 mm) transparent Bayer PC whereas the PC filmlaminated to the polyester side of the coated film intermediate was0.008 inch (0.2 mm) transparent PC film available from GE Plastics,Pittsfield, Mass. Surface resistivity of each PC side was at least1×10¹³ ohms/square but both sides of the film had a static decay time of0.01 second. During the Particle Pick-up Test, this construction did notattract particulate matter when placed over the bed of vermiculite.

Example 8

A static dissipative film was prepared in the manner of Example 5 exceptthe substrate was DBEF having an integral matte surface (sold under thetradename VIKUITI™ by 3M, St Paul, Minn.) and the outer layers werepolyolefin instead of polycarbonate. Thus, MAB/BP mixture was coatedonto the matte surface of the substrate and dried as described inExample 5. Approximately 0.00125 inch (0.03 mm) Soken 1885 transferadhesive (Soken Chemical and Engineering Co.; Tokyo, Japan) waslaminated onto the MAB/BP surface. Polyolefin film having a thickness of0.0019 inch (0.027 mm) was then laminated to the adhesive. Surfaceresistivity of the static dissipative film was at least 1×10¹³ohms/square on each of the polyolefin or the DBEF sides but both sidesof the film had a static decay time of 0.01 second.

Example 9

A conductive polymer mixture was prepared by mixing 0.8 grams of D1012Wdispersion with 17 grams of water containing 0.5 grams of 10% TritonX-100. This mixture was coated onto 0.005 inch (0.125 mm) corona treatedPET film using a wire wound rod to produce a 0.001 inch (0.025 mm) wetfilm. The coating film was dried at 100 C. for approximately 2 minutes.The surface resistivity of the dried conductive polymer coating was5.2×10⁹ ohms/sq. A static dissipative film was then made by laminatingthe conductive polymer film between two 0.005 inch (0.125 mm) layers ofpolyester film each having a 0.003 inch (0.075 mm) coating of pressuresensitive adhesive on one side. The static decay time was 0.02 seconds.The surface resistivity of either side of this static dissipative filmwas greater than 1×10¹² ohms/sq.

Example 10

A conductive polymer film was prepared using a polypyrrole solutiondescribed as a conductive polymer doped with proprietary organic acidsobtained from Aldrich Chemical Company as Catalog Number 48,255-2supplied as a 5% solution in water. The polypyrrole solution, withoutfurther modification, was coated onto 0.005 inch (0.125 mm) coronatreated DBEF-M film using a wire wound rod to produce a 0.001 inch(0.025 mm) wet film. The coating film was dried at 100 C. forapproximately 2 minutes. The surface resistivity of the dried conductivepolymer coating was 2.8×10⁷ ohms/sq. A static dissipative film was thenmade by laminating the conductive polymer film between two 0.005 inch(0.125 mm) layers of polyester film each having a 0.003 inch (0.075 mm)coating of pressure sensitive adhesive on one side. The static decaytime was 0.01 seconds. The surface resistivity of either side of thisstatic dissipative film was greater than 1×10¹² ohms/sq.

1. A method of making a static-dissipative optical construction comprising: providing a non-static-dissipative optical substrate; applying a static-dissipative composition on a major surface of said non-static-dissipative optical substrate, wherein the composition comprises a conductive polymer; and positioning a non-static-dissipative layer over said static-dissipative composition, wherein the construction has a light transmissivity greater than 90% and a surface resistivity greater than 1×10¹³ ohms/sq.
 2. The method according to claim 1 further comprising: applying a primer onto at least a portion of the major surface of said non-static-dissipative optical substrate.
 3. The method according to claim 1 further comprising forming a micro-structured surface.
 4. The method according to claim 1, wherein the construction exhibits a static decay time of less than 2 seconds.
 5. The method according to claim 1, wherein the construction exhibits a static decay time of less than about 0.5 seconds.
 6. The method according to claim 1, wherein the construction exhibits a static decay time of less than about 0.1 seconds.
 7. The method according to claim 1, wherein the static-dissipative composition further comprises a binder.
 8. The method according to claim 7, wherein the binder comprises a material selected from a group consisting of acrylate, melamine, urethane, and combinations thereof.
 9. The method according to claim 1, wherein at least one of the non-static-dissipative optical substrate and the non-static-dissipative layer is a film comprising a material selected from a group consisting of polyvinyl chloride, polyethylene, polyethylene naphthalate, polyurethane, polyethylene acrylic acid, polypropylene, polyester, polycarbonate, poly(methyl methacrylate), polyvinylidene fluoride, polyether, a polyimide, a polyamide, and blends thereof.
 10. The method according to claim 1, wherein at least one of the non-static-dissipative optical substrate and the non-static-dissipative layer is a hardenable resin.
 11. The method according to claim 1, wherein at least one of the non-static-dissipative optical substrate and the non-static-dissipative layer comprises a micro-structured surface.
 12. The method according to claim 1, wherein at least one of the non-static-dissipative optical substrate and the non-static-dissipative layer comprises a multi-layer film.
 13. The method according to claim 1, wherein at least one of the non-static-dissipative optical substrate and the non-static-dissipative layer is a material selected from a group consisting of polarizers, diffusers, reflectors, colored films, mirrors, louvered optical film, and brightness enhancement film.
 14. The method according to claim 1, wherein the static-dissipative layer is a conductive coating.
 15. The method according to claim 14, wherein the coating has a dry thickness of at least 2 nanometers.
 16. The method according to claim 14, wherein the conductive coating is an adhesive.
 17. The method according to claim 1, further comprising at least one additional optical layer contacting a major surface of the non-static-dissipative optical substrate and the non-static-dissipative layer. 